Taking your liability issue first, in many states anyone holding themselves out to have some skill and knowledge in Uechi, who drops by to train in Uechi, would have a fairly high assumption of the risk hurdle to clear if they are injured in a class. This assumes that no one is the class is acting recklessly or is intentionally trying to hurt the visitor.
As a guest in your dojo, you will owe the person a duty of care, but the duty presumes reasonable conduct on your part within the confines of the activity. Someone dropping by a gym for a pickup game of basketball would have a similarly high assumption of the risk hurdle to clear if they were hurt while playing hoops.
It is my understanding, however, that some states have done away with the notion of assumption of the risk, so be sure and check to see what the standard of care is in your locality, and what you need to do to act reasonably.
In California, courts have found that a judo black belt failed to meet the standard of care when he was too forceful with a beginner. You can google the topic for your state, or use FindLaw to check and see if there is any case law in your locality involving martial arts instruction.
As to the experiences, pretty much had them all. Some were amusing, some were educational, some were scary, and some were simply bizarre. I have had one "master" stop my class to lecture about why he was so good and how the stripes on his belt indicated he was a very high rank and what he would teach my class if they joined his dojo. He also refused to demonstrate any kata, because I wouldn't understand his interpretation.
I have had folks who have tried to shake off the rust who discovered that arm conditioning tends to fade over the years. Others who just wanted to spar, and had no control and ended up hurting the black belts they were working with because the black belt was trying to watch out for the returnee.
I have had foreign visitors who expectations of what the class should be and my teaching style didn't exactly mesh. I have also had the mystic visitors, whose ki, chi, psychic powers apparently weren't working that evening. I have had ninjas, kung fu fighters, boxers, and any other manner of martial artist who wanted to try a class.
Following up with one of these folks, I was told Uechi was too extreme a style. (We don't wear pads in my class, except for the knuckles.)
I have had folks from other styles tell me my karate is too hard, and folks from other Uechi schools wondering where the heck I get all this soft sticky technique. Most of the people who are returning want to show me what they know, and perhaps get validation for their prior training.
Most of the high ranks (with the one exception noted above) just want to work out, and generally need to be cajoled into leading any part of the class.
I welcome the visitors. I think it’s great to have my San Chin checked by someone new. I love the interactions, whether they be humorous or educational.
But most of all, I welcome the family. Not to wax too poetic, but there was a time when the patch on one’s gi didn’t matter to anyone doing Uechi. We were family. Uechi brothers and sisters born of hours and sweat and training on dojo, gym, patio and garage floors. We didn’t need to know too much about one another, other than we trained and we did San Chin.
For many of us, the ties and bonds we have created through Uechi have also sustained us through the ups and downs of life. The truly wonderful aspects of martial arts are not so much in the infrequent use of it to defend oneself, but more in the character the training demands we polish, the spirit it demands we forge, and camaraderie it fosters among us.
This sense of family many of us still have is why most of us have a welcome mat out for anyone who has done, is doing, or would like to do Uechi. I love having visitors, and hope you will come back this way soon.
Peace
Robb in Sacramento